Alert archive / North Dakota / Mesoscale Discussions in 2021
Mesoscale Discussion 1337
The Storm Prediction Center issued this mesoscale discussion at Jul 23, 2021, 10:33 PM CDT for 7 counties in Minnesota; 8 counties in North Dakota; 8 counties in South Dakota. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- Jul 23, 2021, 10:33 PM CDT (03:33 UTC)
- Expired
- Jul 24, 2021, 12:30 AM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 388
All 23 counties
Big Stone County, MN, Clay County, MN, Grant County, MN, Otter Tail County, MN, Stevens County, MN, Traverse County, MN, Wilkin County, MN, Cass County, ND, Dickey County, ND, LaMoure County, ND, Logan County, ND, McIntosh County, ND, Ransom County, ND, Richland County, ND, Sargent County, ND, Brown County, SD, Campbell County, SD, Day County, SD, Edmunds County, SD, Marshall County, SD, McPherson County, SD, Roberts County, SD, Walworth County, SD
The radar
The Aberdeen radar (KABR), 59 km from the middle of the area, began a volume at 03:33 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Aberdeen, SD (KABR), launched 00:00Z, 3.6 hours before the alert went out and 120 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 3002 J/kg
- Mixed-layer CIN
- -46 J/kg
- Mixed-layer LCL
- 1613 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 53 m²/s²
- 0-3 km storm-relative helicity
- 89 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 6.9
The text
As transmitted.
657
ACUS11 KWNS 240333
SWOMCD
SPC MCD 240333
MNZ000-SDZ000-NDZ000-240530-
Mesoscale Discussion 1337
NWS Storm Prediction Center Norman OK
1033 PM CDT Fri Jul 23 2021
Areas affected...northeast South Dakota...southeast North
Dakota...west-central Minnesota
Concerning...Severe Thunderstorm Watch 388...
Valid 240333Z - 240530Z
The severe weather threat for Severe Thunderstorm Watch 388
continues.
SUMMARY...Severe gusts or marginally severe hail remains possible
with a cluster of cells moving the North/South Dakota border.
DISCUSSION...A primary cluster of storms continues east/southeast
near the ND/SD border, with new development on the southwest flank.
A 75 mph gust was recently measured in McPherson County SD. VWPs
across ND show increased northwest winds just above the surface,
indicating the deeper cold advection. This is aiding additional
storms on the northwest side of the primary cluster.
Temperatures aloft remain cool due east of the advancing convection,
and the boundary layer remains very moist and unstable. Height falls
with the upper trough will continue, favoring at least a continued
threat across the remainder of WW 388 and perhaps to the east. Parts
of west-central MN may need a watch should the storms continue to
produce severe gusts.
..Jewell.. 07/24/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MPX...FGF...ABR...BIS...
LAT...LON 46239998 46659987 46819947 47059658 46689565 45749551
45329597 45209676 45189913 45250017 45400041 46239998SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 23, 7:44 PM CDT | Mesoscale Discussion | SPC | Aitkin, Carlton, Cass, Lake, Saint Louis | 2 hr |
| Jul 23, 9:07 PM CDT | Mesoscale Discussion | SPC | Lac qui Parle, Lincoln, Lyon, Murray, Pipestone, Redwood and 2 more | 2 hr |
| Jul 23, 11:22 PM CDT | Severe Thunderstorm Watch | SPC | Anoka, Benton, Big Stone, Chippewa, Douglas, Grant and 16 more | 4 hr |
| Jul 24, 1:10 AM CDT | Mesoscale Discussion | SPC | Big Stone, Chippewa, Douglas, Grant, Kandiyohi, Meeker and 9 more | 95 min |
| Jul 23, 7:02 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Dickey, Emmons, Grant, LaMoure, Logan and 5 more | 7 hr |
Nearby
Mesoscale Discussions in North Dakota, 2021Mesoscale Discussions in South Dakota, 2021Mesoscale Discussions in Minnesota, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.